My wife's kindergarten class asked, "What would happen to a tree planted on the moon?" Aside from the obvious that it would die from lack of water/air, what physical effects would happen to a tree exposed to the vacuum of Space?
This is a question for a biologist.
To start with, I guess it would freeze dry, by the water evaporating due to the lack of atmosphere, as Ted observed. If you have forgotten an unwrapped piece of food in the freezer you would know what it means.
Then also the rest of the molecules which are made up mostly of Carbon and Hydrogen would slowly sublimate. If in the sun, much faster.
Now if one assumes a bubble of atmosphere and appropriate water and fertilizer, and the question concerns if the moon soil could support a plant, the answer is , yes, if earth soil microorganisms are introduced into the moon soil where the plant is planted. The technique exists used for improving poor soils. (I recently learned about it from discussions about planting a sour cherry tree in poor soil.)